ABSTRACT
The Internet is the most complex artifact in history. It may turn out to be important or it may not. The transmission control protocol is the standard internet protocol (IP) for the transfer layer. It defines how IP packets are sent back and forth between a sender and a receiver to provide many of the things that IP does not. When confronted with good security and when all other attacks fail, an attacker can always fall back on trying all possible combinations of data (e.g., user identifiers and passwords) until he or she finds one that gets through. In the analogy, a firewall is assumed to resist fire equally in both directions. Four fundamental policy positions are available to network operators. The firewall policy will be the result of these postures and of the applications on the network. A conservative firewall policy is intended to position an institution or network on the paranoid side of restrictive.
